Patch files are the easier way to get SD Remix as you just need a patching program (some form of xdelta) and an SSBM ISO. See Patching SD Remix for more instructions on how to use them.

Source files are the actual changed files that make up the SD Remix mod. This is mostly used for development purposes, though you can also build the SD Remix ISO by replacing some of the original SSBM files with these changed files. Depending on if you’re going to be building an ISO or setting it up to be played with DIOS MIOS, it requires an original SSBM ISO and extracting and/or rebuilding tools. The download is larger and the process is more involved, so we only recommend this method if you’re a developer and you either already know how to rebuild ISOs, or you’re curious about what SD Remix is made up of.